A number of methods for separating, purifying or preparing biological and/or chemical liquid samples currently exist. Fluidized bed chromatography, and separation medium filled chromatography columns have all been employed with varying success to separate and/or purify biological and/or chemical substances of interest from liquid samples with respect to yield, time consumption, purity and cost.
The primary template process for commercial harvest of monoclonal antibodies (mAbs) is to remove the visible (turbidity) cells and cell debris through a clarification train then loading directly onto a traditional bead based bind/elute capture chromatography column.
Clarification is typically a two step process. The first step is either depth filters or a disk-stack centrifuge. Currently fully disposable depth filter are not well suited to use with any current sterilization techniques. Using depth filters in stainless housings allows the use of steam for sterilization, but adds hardware and the need for cleaning and validation of the cleaning. Depth filters are limited in the cell density and total batch size where they are practical. The use of a disk-stack centrifuge takes away some of the performance limitations of depth filters for primary clarification, but brings with it many of its own challenges in cleaning, aseptic operation, and sealability. Secondary clarification is typically performed with depth filters with the same aseptic challenges as when used for primary clarification. The performance limitations for secondary primarily are where a large small particle concentration is present. A final membrane filter is typically employed to for bioburden reduction and to protect the chromatography steps downstream that could be easily fouled by remaining solids.
The ligand of choice for the chromatography step is typically Protein A with cation exchange used occasionally. The hardware required to pack and operate pilot scale and larger chromatography columns is significant, and requires careful packing and characterization. Because of the high cost of the resin and the effort required to pack it into an effective bed the columns are typically cleaned in place and re-used through a campaign or until the end of the resin life.
Current clarification methods struggle with achieving aseptic conditions (continuous centrifuge, disposable cellulosic depth filter devices). Steaming of cellulosic devices currently only safe in capital intensive stainless housings that subsequently require cleaning. Aseptic requirement more significant for vaccine harvest or gray space processing.
In addition current clarification methods struggle to clarify harvests with very high solids or high concentrations of small particulates, and have trouble achieving good yield with low titer harvests.
Recently, clarification methods have alternatively been carried out in installations in which the components in contact with the sample liquid are single-use components.
Such single-use components have the advantage of avoiding cleaning operations, but, to provide the required degree of security, the implementation of an installation with such components necessitates operations of selection, assembly and verification which are relatively complex.
Accordingly, it would be desirable to have process clarification methods and components for treating liquid biological samples and feeds that are convenient to implement, simpler, less expensive, and rely on single-use components that have low demands for bed properties by relying on static binding, and that do not require careful column packing and/or characterization the require specialized equipment and relatively expensive device designs.